RFR(XS): 8049441: PPC64: Don't use StubCodeMarks for zero-length stubs

[Volker Simonis]

Hi everybody,

can somebody PLEASE review and sponsor this tiny, ppc64-only change.

Thanks,
Volker


On Tue, Jul 8, 2014 at 5:45 PM, Daniel D. Daugherty
<daniel.daugherty at oracle.com> wrote:
> Adding the Serviceability Team since JVM/TI belongs to them.
>
> Dan
>
>
>
> On 7/8/14 9:41 AM, Volker Simonis wrote:
>>
>> Hi,
>>
>> could somebody please review and push the following small, PPC64-only
>> change to any of the hs team repositories:
>>
>> http://cr.openjdk.java.net/~simonis/webrevs/8049441/
>> https://bugs.openjdk.java.net/browse/JDK-8049441
>>
>> Background:
>>
>> For some stubs we actually do not really generate code on PPC64 but
>> instead we use a native C-function with inline-assembly. If the
>> generators of these stubs contain a StubCodeMark, they will trigger
>> JvmtiExport::post_dynamic_code_generated_internal events with a zero
>> length code size. These events may fool clients like Oprofile which
>> register for these events (thanks to Maynard Johnson who reported this
>> - see
>> http://mail.openjdk.java.net/pipermail/ppc-aix-port-dev/2014-June/002032.html).
>>
>> This change simply removes the StubCodeMark from
>> ICacheStubGenerator::generate_icache_flush() and generate_verify_oop()
>> because they don't generate assembly code. It also removes the
>> StubCodeMark from generate_throw_exception() because it doesn't really
>> generate a plain stub but a runtime stub for which the JVMT dynamic
>> code event is already generated by RuntimeStub::new_runtime_stub() ->
>> CodeBlob::trace_new_stub() ->
>> JvmtiExport::post_dynamic_code_generated().
>>
>> Thank you and best regards,
>> Volker
>
>